Just to keep everything linked together, your reply partly answers my question, earlier in this topic.
In my not so expert opinion, it sounds like that’s pretty robust.
But for the record - the user who knows someone who made multiple pledges from different accounts says that they were made via Crowdcube’s site. So this is another area where it appears that Crowdcube’s technology has been inadequate.
I appreciate the fact that it’s too late to do anything about that for the current process & too soon to say how you can address this next time though ¯\_(ツ)_/¯